Convert 220 circuit to 110 circuit to be run to new subpanel

Discussion in 'Electrical Forum discussion & Blog' started by C Willard, Oct 24, 2009.

  1. C Willard

    C Willard New Member

    Messages:
    3
    Location:
    Texas
    I have an existing 220V circuit running to my garage using 10-3 with ground wire. I want to convert this circuit to 110V adding a subpanel to the garage and run to recepticles. There will be a freezer and refrigerator.

    Do I use a 30 amp double pole circuit breaker at the main panel and run neutral, red, black and ground to the subpanel?

    How many 20 amp circuits can I add to the subpanel. If only one, can I add a 20 and a 15 amp?

    I know an alternative is converting to 110 V single pole breaker at the main panel with only 1 110V 20 amp circuit, but is it enough for the freezer, refrigerator and more recepticles.
    Last edited: Oct 24, 2009
  2. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,607
    Location:
    Cave Creek, Arizona
    circuit

    Your 220/240 v wire is actually TWO 110/120 circuits. Connect it to the new sub panel, and then install your new breakers in such a way as to spread the load between the two feeds.
  3. C Willard

    C Willard New Member

    Messages:
    3
    Location:
    Texas
    What are the maximum number of circuits and amps per circuit that can come off at the subpanel
  4. Alectrician

    Alectrician DIY Senior Member

    Messages:
    689
    #10 wire = 30 amps per "leg"

    You can put as many 20 amp circuits as you like on it but if you draw over 30 amps the main breaker will trip.
  5. C Willard

    C Willard New Member

    Messages:
    3
    Location:
    Texas
    What's the maximum breaker I can use at the main panel with the 10-3 wire. Can I go higher than 30 amp at each pole?
  6. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,990
    Location:
    New England
    Any single cb must be at or below the max on the wire feeding it, so with the incoming wire you have, no individual breaker after it can be greater than 30A. That does not mean that you can't have individual breakers AFTER that feed that exceed the total. IOW, you can have the sum of the breakers in the subpanel exceed 30A as long as the wires used and the breakers selected individually don't exceed 30A. That way, no set of wires capacity would be exceeded, since the branch breaker or the subpanel feed's breaker would trip first.
  7. jar546

    jar546 In the Trades

    Messages:
    432
    Location:
    USA
    What code cycle are you under?
    What does your electrical inspector say about your plans?
    How much will the permit and inspection cost?
  8. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,607
    Location:
    Cave Creek, Arizona
    breaker

    You can only use a 30 amp, or smaller, breaker at the main panel to feed the #10 wires. WIth 110/120 at the sub panel, you will probably use 15 and 20 amp breakers. Try to balance the loads on both feed wires to even things out.
  9. Alectrician

    Alectrician DIY Senior Member

    Messages:
    689
    Uh oh. Dad's home
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